Games in 3D need a lot of resources to run properly. After all, assets with a lot of polygons can be very taxing for your system. The more they have, the more your computer needs to render. Game studios try to optimize their assets so that they have the least amount of faces possible. With the use of LOD (Level of Detail), you can optimize your rendering without losing any quality.
What is LOD (Level of Detail)?
LOD or Level of Detail is a technique to reduce the computational cost of rendering 3D models. The main model swaps with a simpler asset that has less detail on it without the player noticing it. The number of polygons, textures, and other geometric features in the model are reduced depending on the distance to the camera.
Reducing Polygons
Polygons are one of the most expensive parts of an asset. The more it has, the more computing power it needs to render it properly. Reducing the poly count is one of the most efficient methods to save resources without losing any visual quality. Especially if the model is further away from the camera, no one’s going to notice that it’s missing some faces.
This method is very straightforward and you can feel the difference immediately. Some assets can be reduced to a simple plain, saving you a lot of resources you can use elsewhere instead.
Lower Texture Quality
The same applies totextures. While it is important to have high-quality textures for things that are close to the player, you can gradually reduce it the further it gets away from the camera. After all, who needs a 4k texture on a wall where you can even spot the tiniest crack in the brick when you’re standing hundreds of meters away without the possibility to zoom in?
Getting Rid Of Other Geometrical Features
In some cases, it’s not just reducing the poly count of an asset but removing whole bits and pieces entirely. Nobody is going to notice if a tree has 10k leaves on a branch or just 1k leaves while looking at it from a distance so you can easily reduce their number. Cables, ropes, or other tiny details that merge with their surroundings and are hardly visible from a distance can be entirely removed. It’s very situational how much you can reduce the polygons on a single asset but as long as it goes unnoticed by the player you can get away with almost everything.
Different LOD Systems
If you’re planning on creating a complex 3D project, be it a game or something else, you need to learn how to set up your own LOD Systems if you want to optimize your performance. We are going to look at the most common ways to reduce the level of detail on your assets and how you can set up your own LOD system.
Discrete Levels of Detail (DLOD)
The DLOD method is one of the first things you stumble across if you dive into the topic of LOD. You create multiple versions of your asset, each version with fewer polygons than the one before. LOD 0 is the whole asset with its full poly count while LOD 1 has only 50% of the original while LOD 2 has only half the faces of LOD 1 and so forth. Reducing the poly count by half is a general rule of thumb but sometimes you need to tweak it around a bit depending on the type of asset. You should also half the texture resolution the further down you go with your polygons and swap it on the different versions.
Every LOD is assigned to a specific distance to the camera where it gets swapped out with the higher or lower version of itself. You should also try to limit the amount of LODs to around 4 because the more you use the more space and computing power it needs.
When an LOD switches in too fast while being too close to the camera a player can notice the sudden change in visual. This is called a “pop-in” and has to be avoided at all costs. Pop-ins can be very distracting and make your game look very unpolished & rough if it happens very frequently so make sure you keep that in mind.
Continuous Levels of Detail (CLOD)
The CLOD method can be combined with the DLOD method to optimize the level of detail of your assets even further. Instead of switching out the whole assets, the algorithm reduces the level of detail on the side of the object that the viewer can see at the moment. For example, if you look at the front of a building it renders in the highest while its backside only loads in with the lowest quality. There is also the possibility to completely remove parts that can’t be seen by the player but you have to take into account what would be more efficient in certain situations.
How To Create Your Own LODs
Creating LOD systems yourself sounds rather daunting at first but in fact, it’s easier than you might think. We’re going to show you the easiest ways to create your own LODs for your assets and what programs you can use for it.
Manually
Creating your LODs manually gives you the most control over how you want them to look and how much you are going to reduce the details on your asset but of course it’s also the most time-consuming method. So if you’re aiming for a bigger project you should probably look into more automated systems.
Automatically
Nowadays there are a lot of programs that have built-in features or extra plug-ins you can use to generate the different levels of LOD. Simply set the desired number of LOD and the distance from the camera and you’re good to go. Nevertheless, you should always double-check the created assets to see if their UVs, textures, and geometry are to your liking or if they need some polishing.
Programs For LOD Creation
There are a bunch of different programs you can use to set up your LODs. Every single one of them comes with its perks so try them out and find what suits you best.
Blender
Blender is a completely free program. You can easily reduce the number of faces of your asset by using the decimate modifier that comes with it. You can also manually adjust the loops to however you want afterwards if you run into any problems.
3DS MAX
3DS Max has a plug-in called ProOptimizer that also generates LODs for you. It’s one of the industry standards used in game studios to create & animate props, characters, and other things. This program is not free and is very pricey. So unless you’re already in a professional setting, we wouldn’t recommend this software for beginners.
Maya
Just like 3DS Max, Maya is a licensed program that has its own LOD function called ‘Generate LOD Meshes‘. In both programs you can tweak the generated LODs afterward if you are not satisfied with the results. While Maya can also be used for video games it’s more likely used for film and VFX purposes.
Houdini
Houdini also can automatically generate multiple LODs using PolyReduce SOP. While the full version costs quite a bit, there’s also a free version for students and hobbyists called Houdini Apprentice.
Unreal Engine
The Unreal Engine already has a built-in LOD system that automatically generates LODs for you. You choose how many you want and at which distance to the camera they load in.
LODs are a must-have for 3D-based games. It influences the player’s experience and the rendering time of any system. Even if your game doesn’t include hundreds of assets, it’s worth looking into it. To make the gameplay feel better and smoother, even on lower-end hardware which makes it more accessible for people.
If you are interested in creating your own game, here you’ll find a list of tools you need to start:
Game Development Essentials: Tools You Need to Start Creating Your Own Game
Leave a Reply